Project Summary/Abstract Through the research and training described in this K23 proposal titled A Behavioral Economic Intervention to Reduce Marijuana Use in Truant Youth, the PI (Dr. Yurasek) will acquire the necessary skills to become an independent clinical researcher conducting patient-oriented research that will improve the efficacy, accessibility and cost-effectiveness of marijuana use interventions within the juvenile justice system. Despite the effectiveness of parent and family based interventions for juvenile substance use and recidivism, they can be lengthy, costly and difficult to implement in court and community settings. These interventions often require adolescents and family members to attend multiple sessions, and may not be appropriate for families and settings with limited resources. Brief motivational interventions (BMIs) have demonstrated efficacy with adolescent substance users, and approaches that combine parent and adolescent involvement have been associated with more robust outcomes among youth. However, parent-based BMI?s do not address behavioral economic mechanisms such as substance -free activities or delayed discounting which may limit their efficacy with truant youth experiencing a disruption of substance-free reinforcement. The aim of this proposal is to adapt a brief (one session) behavioral economic intervention to reduce marijuana use that involves truant youth and their parents. This project will examine the acceptability, feasibility, and initial efficacy of this intervention with adolescents referred for services as part of a juvenile specialty (truancy) diversion program. The 4 research aims are to adapt a brief behavioral economic intervention for parents and adolescents, test the feasibility of the intervention, conduct a randomized pilot trial, and conduct a cost-benefit analysis of outcomes to ensure the protocol addresses the needs of the larger juvenile justice and court systems. In this mentored career award, the PI will facilitate her career goals working with an experienced and knowledgeable team of mentors (Drs. Cottler, Tolou-Shams, and Fisher) and collaborator/contributors (Drs. Park, Murphy, and Spirito) to master four areas of training relevant to this proposal 1) Substance use treatment research in juvenile-justice settings 2) community-based intervention development and adaptation for substance-using adolescents; 3) qualitative data collection and analyses; and 4) developing basic competencies in economic evaluation of legal, social and mental health outcomes. Successful completion of this study will provide information on the benefits of using behavioral economic theory to reduce marijuana use and potentially reduce costs associated with treating marijuana using truant youth.